Mintel offers market research reports covering U.S. and International marketplaces. Each report combines data and analysis of the competitive landscape, market share analysis, and consumer profiles. Once you log in to Mintel Academic you can use the search bar at the top of the page the find reports on pizza, food retailing, frozen foods, and consumers. The report linked to below will give you a head start on the pizza market in the United States but should not be the only report from Mintel that you use for secondary research.
Pizza - US - October 2018: This report looks at pizza in the U.S., including the consumer, market, and brands.
IBIS World Industries and Markets includes comprehensive US Industry Reports for over 700 US industries with a NAICS code, selected Global Industry Reports, and UK Brexit Impact Statements. Also included are US Business Environment Profiles, helpful for assessing industry risk factors. Searchable by NAICS code, company name or keyword. Below are two reports from IBIS that will get you started with industry information. At any time in IBIS you can search for industry information by using the "Search" box at the top of each page. For remote access to IBIS use the link above and then search for Frozen Pizza or Froze Foods.